Molotov cocktail is such a simple and perfect solution. Any tank including an M1 Abrams is disabled by a fireball at its air intake. The engine quits due to lack of oxygen.

The electric thing doesn't make sense. The current would flow through the outermost metal parts and leave the crew completely unaffected. Passengers in a car are safe from lightning because the current flows through the body of the car. Tires are insulators, but this is irrelevant because lightning can spark across the 1ft of air between the bottom of the car and the ground.